You could build the Pd-extended package on yoyur machine with the right compiler flags, then everything should be 64-bit. Even better would be to help generate debian packages from the Pd-extended build system. That is happening already with the PlanetCCRMA RPMs.
mkdir pure-data cd pure-data cvs co -r branch-v0-39-2-extended abstractions cvs co -r branch-v0-39-2-extended doc cvs co -r branch-v0-39-2-extended extensions cvs co -r branch-v0-39-2-extended externals cvs co -r branch-v0-39-2-extended pd cvs co -r branch-v0-39-2-extended packages cvs co -r branch-v0-39-2-extended scripts cd packages/linux_make make install && make package
do the /{packages,scripts} dirs only exist in the branch-v0-39-2-extended branch? can one just check out those 2 dirs, then use them with the MAIN branch's /pd dir? since thats the only one that has a chance of working mostly correctly on 64bit..